With U.S. venture capital investment slowing down, companies at all stages of development could face trouble raising fresh capital.

A lot gets written about the travails of so-called unicorns, with their billion-dollar valuations, trying to prove their worth to new investors when they run short of cash.

But some investors think the real crunch could be for startups looking for Series B or C rounds. These companies often don’t have the revenue or other resources to maneuver if newly cautious investors won’t open their wallets.

It is early to get a read on the scope of this situation, but the latest data from Dow Jones VentureSource shows that it has become tougher for startups raising second rounds of venture capital.

Overall venture financings in the U.S. declined 11% in the first quarter with 863 rounds versus 967 a year earlier. Second rounds fell to 205, a 14% decline compared with drops of 6% and 9% for first and later rounds, respectively.

When it came to dollars invested, the difference was even greater. Second-round investment fell 34% from a year earlier, to $2.03 billion. Later-stage investment was down 25% while first rounds fell by only 4%. Overall venture capital investment in the U.S. was off 24%, for a total of $12.56 billion. That total doesn’t include deals that involved only corporations or other non-venture investors.

Startups raising second rounds in the first quarter generally had to make do with less money, according to the VentureSource data. The median amount raised was down 39% from a year earlier, to $5.15 million versus $8.5 million. It was $8 million in the third quarter of 2015 and then dropped to $6.5 million in the fourth quarter as the current investment slide began.

“Great companies showing a lot of traction have absolutely no issue whatsoever,” says Maria Cirino, co-founder and managing partner at Boston’s .406 Ventures, but others will struggle to raise B and C rounds.

“We’re entering a period of a lot of smaller-company consolidation,” she said.